Other authors suggest that the success of, and selection for, bipedal locomotion
was due to sentry behavior, standing briefly upright, as baboons do.
Kohlsdorf and Biewener (2006), for example, observed bipedal locomotion when lizards moved over medium and high obstacles, which could be related to an enhancement in environmental perception.
In this paper, we describe, for the first time, bipedal locomotion in South American lizards.
The body posture, as a whole, diverged a lot during bipedal locomotion between the two species we analyzed.
Yet still there seems to be no correlation between tail angles and bipedal locomotion (Irschick and Jayne, 1999).
torquatus exhibited considerably higher trunk angles (Table 1), as in many previous values on bipedal locomotion (see Urban, 1965 for a review).
Even though lizards with digitigrady seem to achieve higher speeds than the ones with plantigrade posture during bipedal locomotion (Reilly and Delancey, 1997; Irschick and Jayne, 1999), it seems there is no correlation between foot posture and lizard bipedality.
The common elements of habitat associations with saurian bipedal locomotion were first considered by Snyder (1952), who divided bipeds into two groups: primarily terrestrial species living in open, sandy or rocky areas; and lizards living in brushy or forested areas that may be classed as arboreal or semi-arboreal.
Earlier claims that bipedal locomotion maximize speed (Snyder, 1952) were questioned recently by Irschick and Jayne (1999) who found no arguments for a speed advantage of bipedal performance.
Functions of the tail in bipedal locomotion of lizards, dinosaurs and pterosaurs.
Bipedal locomotion of the lizard Basiliscus basiliscus.